Electromechanical design of a magnetic device for monitoring volume and property changes of

Abstract

In a wearable device and a method of using limb perimeter and acceleration to monitor changes in volume and property of human interstitial fluid associated with both normal and disease conditions, raw data is transmitted from the wearable device to an external device for storage and evaluation. This data is compared and compared to reference information for individuals and larger populations, and assessed to achieve health and clinical significance. Relevant messages relating to the state of the individual may be transmitted to relevant parties, such as patients, caregivers, and medical professionals.

Description

Background Art

[0001] Fluid balance is an important aspect of human physiology. The body automatically adjusts to try to maintain the body's fluid levels under various conditions. Certain medical conditions (such as heart failure, kidney disease, and others) can overwhelm the body's regulatory mechanisms, resulting in excessive fluid retention or fluid overload, which can manifest as peripheral edema or limb swelling, for example. Summary of the invention

[0002] Fluid retention and edema, or swelling of the limbs, can be associated with and predict impending decompensation events in heart failure patients. Unfortunately, patients often do not have good tools to recognize the signs of worsening conditions. This often forces patients to the hospital for intervention. This is frightening, costly, and can be life-threatening.

[0003] Measuring and managing fluid balance is associated with many aspects of human health, such as heart health, and any number of disease states and drug intervention trials could benefit from an improved wearable device that could detect early warning signs of new or worsening medical conditions in areas that could include, but are not limited to, nephrology, cardiology, sports medicine, prenatal care, migraines, drug trials, and the like. BRIEF DESCRIPTION OF THE DRAWINGS

[0004] The detailed description is described with reference to the accompanying drawings, which show aspects of one or more embodiments described herein, in which the left-most digit(s) of a reference number identifies the figure in which the reference number first appears. The use of the same reference numbers in different figures indicates similar or identical items.

[0005] Figure 1 An isometric view of an example device that may be configured to monitor changes in the volume and properties of a human body's interstitial fluid is shown.

[0006] Figure 2 Shown with Figure 1 Exploded views of example measuring assemblies, winder cassettes, straps and fasteners of the example corresponding device shown.

[0007] Figure 3 An exploded view of the winder cassette, straps, and buckles that remain when the measurement assembly is removed in some embodiments is shown.

[0008] Figure 4 is a top view of the winder box relative to the straps and fasteners.

[0009] Figure 5 The winder box in assembled state Figure 4 Partial section view AA.

[0010] Figure 6 is a side view of the device, which may correspond to Figure 1 The device shown.

[0011] Figure 7 It is taken along line BB Figure 6 Detailed cross-sectional view of the measurement assembly, winder cassette, straps and fasteners of the example device shown.

[0012] Figure 8 is an isometric view of a device that may correspond to Figure 1 The device is shown with the housing of the measuring assembly removed.

[0013] Fig. 9 A graph showing normal swelling (eg, limb swelling) for a hypothetical heart failure patient over a 12 day period.

[0014] Fig.10 Shown is an 8-day graph of compensatory swelling events (eg, ankle swelling) associated with fluid retention related to increased salt intake in a hypothetical heart failure patient.

[0015] Fig.11 A graph of a hypothetical episode of decompensated fluid retention, such as one preceding hospitalization for heart failure, is shown.

[0016] Fig.12 An example of a circuit is shown that demonstrates the efficacy of integrating interstitial fluid volume monitoring with determined outcomes via the device.

[0017] Fig.13 An example of an integrated medication log and ankle circumference history is shown.

[0018] Fig.14 Shows an example architecture for implementing monitoring changes in the volume and properties of a patient's interstitial fluid.

[0019] Fig.15 Various components of a measurement assembly are shown arranged in accordance with one or more embodiments described herein.

[0020] Fig.16 Shown Fig.12 An example of a database server is shown.

[0021] Fig.17 is a flow chart of an example process that may be performed, at least in part, by a measurement component for measuring a limb circumference of a subject, generating a waveform of the measurement over time, and outputting an indication of a condition exposed by the waveform.

[0022] Fig.18As another example, an isometric view of a device that may be configured to monitor changes in volume and properties of human interstitial fluid is shown.

[0023] Fig.19 Shown with Fig.18 Exploded views of example measuring assemblies, winder cassettes, straps and fasteners of the example corresponding device shown.

[0024] Fig. 20 An exploded view of the winder cassette, straps, and buckles that remain when the measurement assembly is removed in some embodiments is shown.

[0025] Fig.21 An example of a digital circuit is shown that can be implemented to perform quadrature decoding including revolution (digital through a 0 degree reference angle) count detection in software at a fraction of the power used by some microprocessor quadrature decoder circuits.

[0026] Fig. 22 is a top view of the winder box relative to the straps and fasteners.

[0027] Fig.23 The winder box in assembled state Fig. 22 Partial section view AA.

[0028] Fig.24 is a side view of the device, which may correspond to Fig.18 The device shown.

[0029] Fig.25 It is taken along line BB Fig.24 Detailed cross-sectional view of the measurement assembly, winder cassette, straps and fasteners of the example device shown.

[0030] Fig.26 is an isometric view of a device that may correspond to Fig.18 The device is shown with the housing of the measuring assembly removed. DETAILED DESCRIPTION

[0031] Interstitial fluid volume is a key medical issue for patients with conditions such as decompensated heart failure, decreased kidney function, and similar physiological conditions. In an example of particular interest, increases in interstitial fluid volume are associated with decompensated heart failure. A single measurement taken from time to time, perhaps at a doctor's appointment, can produce wildly different and conflicting results each time, depending on the random time of day of the appointment and other factors. In the absence of more sophisticated measurements, doctors often resort to rough approximations to determine whether swelling is present, such as pressing their fingers on a person's ankle, which is equivalent in efficacy. Furthermore, the lack of a practical and rigorous medical measurement limits the usefulness of this physiological parameter.

[0032] Previous limb circumference monitoring methods have focused on measuring circumference at known locations on the limb. The devices and techniques described herein do not rely on known locations on the limb, but instead measure at a minimal circumference that indicates a measure of interstitial fluid volume regardless of where the measurement occurs.

[0033] In some embodiments, the device includes a strap that is configured to apply only a slight tension of the strap around a limb, which can be achieved by a design that includes one or more of lightweight components, material properties of the strap, and width of the strap. These parameters, as well as the activity of the limb, can all be combined to allow the device to rest at the minimum circumference of the limb, so that the device continuously senses the minimum circumference of the limb without unnecessary pressure around the limb at the measurement point. For example, when the device is used to measure the volume of a wrist or ankle, it is located at or near the minimum circumference of the limb, so that the measurements can be compared over time. Due to construction details, the device can also be placed in different repeatable initial positions. Movement of the limb (such as standing or walking) helps to facilitate movement of the device on the limb.

[0034] In addition to moving along the axis of the limb, the device can also rotate about the axis of the limb. Typically, the cross-section of the limb is not circular. As the device rotates about the circumference, the area of ​​the winder box against the limb has been minimized, and the strip can more closely conform to the actual shape of the limb. Therefore, the device can allow consistent measurements regardless of the rotational orientation of the device about the axis of the limb.

[0035] The devices described herein can be configured to measure limb circumference and acceleration intermittently, periodically, and / or continuously, and analyze circumference measurements, device, and / or subject orientation, including comparing the current state or trend to the patient's baseline, normal, or desired state. The difference between the measured state and the desired state can be used as an input to guide decisions about the subject's diet, activity, and treatment (including medications in some embodiments) to move the subject toward the desired state and avoid potentially life-threatening events (such as hospitalization for dyspnea in a heart failure patient), among other events (such as those described herein).

[0036] One aspect of the device may include a low force tensioning element and may be configured to include a distributed load over a large area using, for example, a lightweight strap (in one example, less than 1 / 2 ounce, including the device) to allow for uniform force distribution. Gravity acting on the mass of the device may generate forces. Mechanisms that hold the positioning device in close contact with the limb may generate additional forces. For example, the tension applied by the device, particularly by the strap under tension, to the subject's skin may be less than or substantially equal to (there may be some slight compression of the skin) the interstitial fluid pressure at the site and distributed over the entire surface of the strap, so that the friction against the skin is balanced by the gravity on the weight of the device. These combined represent a net force applied to a specified area. One embodiment of the device may provide a broad surface approximately 25 mm wide, which is arranged around the limb to distribute a gravity load of approximately 11 grams applied along the axis of the limb and a constant spring force load of approximately 10 to 40 grams that holds the strap close to the limb.

[0037] In at least one embodiment, the disclosed device measures circumference with the aid of a magnetic circuit and a strap that wraps around a limb. The magnetic circuit includes or cooperates with a magnet and a magnetic sensor. As the limb changes size, the strap expands and contracts via the strap housing and tensioning mechanism, which allows the magnet to rotate and the magnetic sensor to detect the rotation angle of the reel associated with the increase and decrease in circumference of the limb.

[0038] For example, when a person lies down, the interstitial fluid in the body is distributed more evenly across the length of the body. However, when a person stands or sits in a relatively upright position, the fluid is redistributed to the limbs due to gravity. This effect is more pronounced in the lower limbs.

[0039] In one embodiment, the device can be worn nearly continuously, and circumference and orientation data are collected at specified time intervals and processed to determine daily swelling patterns and average daily swelling for each individual. Intra-day circumference changes associated with redistribution of interstitial fluid from lying to standing are greater than circumference changes associated with fluid retention of concern associated with a health or medical condition requiring attention. Thus, longitudinal fluid retention can be detected using multiple circumference measurements over a circadian cycle.

[0040] Careful quantification and tracking over time have shown that even changes in fluid volume of only a few millimeters on average, which are relevant physiological information, can be important signs of disease progression, but this is not visible in a single examination or sometimes even on routine examinations and requires more precise measurements than might be obtained by visual inspection alone. Taking multiple measurements of the minimum limb circumference typical of limb narrowing at the ankle or wrist may be beneficial, as limb circumference can be a close indicator of interstitial fluid volume.

[0041] The device can also measure other physiological parameters, such as heart rate, peripheral capillary oxygen saturation (SpO2), respiratory rate, and non-invasive blood pressure (NIBP). By emitting light of different frequencies and evaluating the return energy, a variety of physiological phenomena can be evaluated. For example, using green light to sense heart rate and measure peripheral edema can confirm the discovery of swelling events, increase certainty, and more accurately assess the progression of decompensation events. Similarly, for example, using red and infrared light in combination with stress testing to assess blood oxygenation can provide valuable information about the current limitations of the oxygen delivery system. This can further confirm and calibrate peripheral edema measurements and appropriately adjust the response to the patient's changing condition. It is also conceivable to use optical measurements to assess non-invasive blood pressure in a patient.

[0042] Non-invasive blood pressure is used to define and adjust patient treatment, including the selection and dosage of medications. Physiological parameters can be collected on a separate device, such as weight using a scale, or NIBP using a device including an inflatable blood pressure cuff, and used to analyze the patient's condition.

[0043] Monitoring (particularly continuously monitoring) a physiological parameter on a remote device, such as the remote device described herein, may require aligning the time of data collection by the device with an established time standard external to the device, such as Coordinated Universal Time (UTC), where the data may be stored and analyzed outside of the device. The device may calculate a relative time, such as the time from initial startup as the time at which the measurement was taken, which relative time may then be resolved to actual time when used with an external device synchronized to a universal time standard, thereby determining the measurement time with sufficient accuracy for planned use. This approach may eliminate the need to perform at least some clock synchronization on the device at startup and during use, thereby reducing operational complexity and power requirements, compared to synchronizing a real-time clock on the device using other timing methods. In order to integrate treatment plans with patient outcomes, medication logs may be collected to correlate modifications in treatment plans with patient outcomes.

[0044] In some embodiments, power requirements can be minimized by making the device (specifically, its processor) in sleep mode most of the time. By using timers and interrupt circuits, the device can still respond to programming and real-time events and wake up appropriately when needed. For this reason, in at least one embodiment, the angle sensing component is connected to a comparator to generate an interrupt when the reel rotates 0 and 180 degrees. The interrupt rate associated with the rapid extension or retraction of the strip can be used to wake up the processor. By comparing with the integrated processor or external orthogonal detection that remains powered on, significant power savings can be achieved, thereby extending battery life. In addition, this interrupt circuit can be used to trigger the processor to enter Bluetooth broadcast mode or other communication protocols, or other variable parts of the software. In some embodiments of the device, an accelerometer can be used as an interrupt source to trigger additional actions of the processor, such as starting other variable parts of the communication protocol or software in response to detecting a change in position or orientation.

[0045] Figure 1 An isometric view of an exemplary device 100 that can be configured to monitor changes in volume and properties of interstitial fluid in a human body is shown. The device 100 can include, among other components, a device assembly that includes a measurement assembly 105, a winder box 110, a strap 115 configured to be placed around a subject's limb, and a fastener 120. In at least some embodiments, the subject can wear the device 100 around the lower arm (i.e., below the elbow) or the lower leg (i.e., below the knee), but the teachings herein can be applied to other body parts, particularly body parts with axial portions, and therefore should not be considered limited except by the type of data required and the location where the data may be obtained.

[0046] The measurement assembly 105 can house an electronics subassembly to obtain data and communicate the data or information based on the data. The electronics subassembly can include a sensor and associated electronics that, in some embodiments, can perform an analysis of the sensor data and output results of the analysis and / or recommendations or instructions based on the results. In some embodiments, the electronics subassembly can include a sensor portion that includes one or more magnetic sensors positioned relative to one or more corresponding magnets on the winder box 110, as described more fully below.

[0047] The winder box 110 typically cooperates with the strap 115 to achieve a loosely tensioned but snug fit to the limb even in the presence of severe swelling. Even in the presence of severe swelling, the device 100 typically does not fit tightly to the limb. In fact, the strap 115 and winder box 110 are configured so that the strap 115 can extend and retract as the limb swells and contracts, thereby enabling a substantially constant force to be applied to the limb. In some embodiments, the winder box 110 in combination with the strap 115 and the fastener 120 can be a replaceable component that can be easily replaced by the user if the winder box becomes dirty or broken.

[0048] Figure 2 Shown with Figure 1 An exploded view of an example measurement assembly 105, winder box 110, strip 115, and fastener 120 of the device 200 corresponding to the illustrated example. The housing 235 is configured to accommodate one or more of: a battery drawer 205 for supporting a battery 210 therein; an electronics subassembly 215, which includes a radio module 220, an angle magnetic sensor 240, and one or more strip size magnetic sensors 245; an insulator 225 and a gasket 230. An identification label may be applied to the housing 235, but no limitation should be inferred. Etched labels, printed labels, etc. may be used. In fact, the device may not have an identification label. The measurement assembly 105 can be substantially fluid-tight to prevent the ingress of bodily fluids.

[0049] The battery 210 may be a so-called coin-type battery, which is any type that meets the power and size requirements of the device 200, particularly the power requirements provided to components on the electronics subassembly 215 and other components, and is sized to fit within the battery drawer 205. In some examples, the battery 210 may be captured between the electronics subassembly 215 and the top of the housing 235. In some embodiments, another portable power source may be used, such as a rechargeable battery, a fuel cell, a storage capacitor, energy harvested from the patient, energy harvested from the environment, etc.

[0050] Insulator 225 may be an electrical insulator and thus may be positioned to insulate battery 210 from electronics subassembly 215 so that battery 210 may be replaced without contacting electronics subassembly 215 or any components or wiring on the electronics board substrate. In some embodiments, insulator 225 may be embossed or printed with configuration information for device 200 or any of its components, such as a version.

[0051] The electronics subassembly 215 may be a printed circuit board and include electronic components that control and perform limb circumference sensing. In at least some embodiments, the limb circumference may be used by an onboard control system or transmitted to a remote computing device that runs an algorithm on data from the sensed limb circumference, outputs a message, and generates a graphical result showing the measurement value over time, which may be interpreted by a medical professional (for example) to gain insight into the current condition of the patient wearing the device 200. In some embodiments, the electronic components may include one or more magnetic sensors (such as magnetic sensors 240, 245), one or more optical sensors, one or more processors, memory, and accelerometers. The memory may store instructions that, when executed by one or more processors, cause one or more processors to perform various operations described herein. In at least some embodiments, the magnetic sensor may detect the limb circumference. In at least some embodiments, the accelerometer may detect the orientation and movement of the patient and output data that may be used by the onboard control system or transmitted to a remote computing device to determine the patient's activity level. For example, using information received from an accelerometer, the device can detect, accumulate, store and / or transmit accelerometer measurements at a sufficiently high frequency and correlate that information with circumference readings to provide an adequate representation of the effects of gravity on the limb and limb activity during the time between circumference measurements.

[0052] The radio module 220 can transmit a digital or analog signal (e.g., containing patient motion information) to an external device. For example, the signal can be transmitted to a nearby computer, smart phone, tablet computer, etc., which has the processing capability to receive the signal, analyze the data provided by the signal, output instructions or commands, and / or relay the signal to a remote computing device such as a server, computer, or database (e.g., in a doctor's office or data center).

[0053] Gasket 230 is configured and positioned to seal housing 235 and prevent intrusion of dust or water that could damage sensitive components inside. For example, gasket 230 can be positioned between housing 235 and battery drawer 205. Gasket 230 includes, but is not limited to, insulating materials suitable for its purpose.

[0054] The measurement assembly 105 can be configured such that the insulator 225 and the electronics subassembly 215 including the radio module 220 are inserted into the housing 235. The battery 210 can be attached to the battery drawer 205 by a snap fit with a gasket 230 positioned where the battery drawer 205 meets the housing 235 to facilitate easy removal of the battery drawer 205 to replace the battery 210. In this example, the battery drawer 205 can be snapped into the housing 235, thereby compressing the gasket 230, which seals the interior of the housing 235 to prevent dust or water intrusion. The winder box 110 can then be assembled to the measurement assembly 105 with the aid of a stopper that holds the measurement assembly 105 and the winder box 110 (including the strip 115) together.

[0055] The distal end of the strip 115 passes through the body of the fastener 120 and is secured by adhering the strip 115 to itself by heat bonding the end to the body of the strip 115 with an adhesive material. However, it should be understood that many other methods of bonding, such as bonding the material of the strip 115 to itself or to the fastener 120, crimping, and the like, are within the scope of the present disclosure.

[0056] The buckle 120 may be coupled to the electronics subassembly 215 via a latching feature that engages the geometry of the battery drawer 205 in the electronics assembly 215 so as to wrap around the limb.

[0057] The winder box 110 can be configured to accommodate straps of different lengths, allowing the device 200 to accommodate a wide range of applications, such as from a small wrist to a large swollen leg. The size of the device can be defined by the length of the fixed strap 115. The winder box 110 can be assembled and marked to identify the strap size, such as small, medium, large and extra large. If the "size" is readjusted or calibrated, the size data can be collected, stored and updated as needed.

[0058] In some embodiments, the housing 235, battery drawer 205, and / or fastener 120 can be 3D printed from materials such as Siraya Tech Blu resin and Siraya Tech Blu mecha nylon resin using a mask stereolithography (MSLA) process. The gasket 230 can include Poron (polyurethane foam). The strap 115 is generally flexible and inelastic and can be made of a biocompatible porous material for patient comfort. As an example, the material can be an open weave, 80 threads per inch polyester fiber with a fused edge, 0.008" Teslin (PPG, Barberton, OH) or Tyvek (Wilmington, DL), or a non-woven open fabric such as embroidery stabilizer.

[0059] Figure 3 An exploded view of the winder box 110, the strip 115, and the fastener 120 that remain when the measuring assembly 105 is removed in some embodiments is shown. The winder box 110 can include a winder box frame 330, a spring 315, and a reel 320. The winder box frame 330 can include a capture feature 340, which can include a strip size magnet 335. The capture feature 340 can further include a spring coupler formed by a pin 344 attached to the winder box frame 330. The reel 320 can be cylindrical and include an angle magnet 325. The strip 115 can be wound around the reel 320 when installed in the winder box frame 330, as described below. In some embodiments, the winder box 110, the strip 115, and / or the fastener 120 can be replaced individually or as a combination including any two or all three.

[0060] The winder box 110 can be configured such that the spring 315 is attached to the capture feature 340 of the winder box frame 330 and the interior of the spool 320. The spring 315 can provide a substantially constant spring force load (e.g., approximately 10 grams to 40 grams) that is sufficient to hold the strap 115 snugly to the limb without unnecessary, uncomfortable pressure.

[0061] The strip 115 is attached to and wound on the spool 320. An angle magnet 325 may be pressed or otherwise fitted into an opening, gap, or recess of the spool 320 such that it is opposite the angle magnetic sensor 240 on the electronics subassembly 215 of the measurement assembly 105. A strip size magnet 335 may be pressed or otherwise fitted into an opening, gap, or recess of the winder cassette frame 330 such that it is opposite one or more of the strip size magnetic sensors 245 on the electronics subassembly 215 of the measurement assembly 105. The magnetic sensors 240 and 245 are configured and positioned to sense the magnetic fields of the magnets 325 and 335 passing through the housing 235.

[0062] The action of increasing and decreasing the length of the strip 115 as the limb expands and contracts can be accomplished by a tensioning mechanism that includes a spring 315 within a winder box frame 330 and a reel 320 that can accommodate a portion of the length of the strip 115 wound on the reel 320. In some embodiments, the spring 315 can be a constant tension spring. As the limb expands, the strip 115 is unfolded, thereby increasing the length of the strip 115 to accommodate the increased circumference of the limb, while maintaining the constant tension of the strip 115 around the limb by the constant force applied by the spring 315. The tension of the strip 115 can match the interstitial fluid pressure and elasticity of the skin so that the device expands and contracts without producing noticeable indentations in the limb. In this regard, and in conjunction with other embodiments described herein, it should be understood that the constancy of force and tension does not need to be precise, but rather within a reasonable tolerance range that enables the device to perform its function of measuring limb circumference according to the principles outlined in the present disclosure, particularly measuring the difference in limb circumference relative to a baseline or other reference.

[0063] The angle magnet 325 installed in the reel 320 can be sensed by the angle magnetic sensor 240, so that when the winding and unwinding of the strip 115 causes the reel 320 to rotate, the rotation degree of the reel 320 can be identified by the signal output by the angle magnetic sensor 240 and received at the electronic device component 215 electrically connected to the angle magnetic sensor 240.

[0064] The angle magnetic sensor 240 can be composed of multiple resistor elements that are arranged to output a set of variable signal strength voltages. In at least one embodiment, these signal strength voltages correspond to the sine and cosine of the rotation of the angle magnet 325 embedded in the reel 320 relative to the angle magnetic sensor 240. This can be achieved, for example, by a full-bridge sensor based on spintronic technology (a suitable sensor currently produced by NVE Corporation of Eden Prairie, MN) because this produces an extremely low-power construction that is relatively insensitive to the distance and axial misalignment between the angle magnet 325 and the angle magnetic sensor 240. Since the diameter of the reel 320 defines a known circumference by the formula C=Pi×D, the diameter can be converted into an accurate change in length measurement when the strip 115 expands and contracts. The diameter of the reel 320 can be determined / calibrated when each device is manufactured.

[0065] In addition to measuring the rotation of magnet 325, the circuit can also retain information about the rotation history. In this example, quadrature detection can be implemented in software or hardware to track the current rotation or number of revolutions. In at least one embodiment, quadrature detection can be achieved by using a comparator circuit connected to an interrupt function on the processor. But in other embodiments, dedicated circuit counting and logic components or integrated functions within the processor itself can take on this function. When the strip 115 is wound around the reel 320 for more than 360 degrees, the rotation count is maintained. The rotation count, together with the current angle measurement value, enables the software to calculate the total rotation degree. The diameter of the reel 320 is combined with the total rotation degree, together with the length of the manufacturing strip 115 when the spring 315 is not used, the length of the measuring assembly 105, and the fastener 120, the total circumference measurement value can be determined.

[0066] Additional considerations may be involved when calculating the total length. As noted above, the strip 115 changes the effective diameter of the winding portion and the circumference on the reel 320 as the strip 115 is wound on the reel 320, layer by layer. To account for this, the rotational history and manufacturing design of the winder cassette 110 may be identified and a diameter change consistent with the thickness of the strip 115 and the number of turns of the strip material around the reel 320 may be applied.

[0067] When the winder box 110 is manufactured, the length of the strip 115 is controlled when the spring 315 is in a relaxed and unused state. If the rotation angle of the magnet 325 is consistent with the reference corresponding to the manufactured relaxed orientation, and the rotation history shows no additional winding, and the angle does not shake due to wearing, it can be assumed that the device is not worn. In some embodiments, the spring 315 can retract the strip 115 to the original position, which can be read by software that is executed to interpret the signal representing the detected angle of the reel 320 using an indicator or message output. The detection of these states can also be used to indicate whether the device is worn. In some embodiments, data from the device 100 in the "not worn" state can be ignored when evaluating the wearer's condition. Further, if this state persists, the patient can be contacted or checked for any problems with the patient wearing the device 100.

[0068] The device 100 can adapt to a range of limb sizes in at least two ways. For example, by constructing the winder box 110 as in the example described above, a large winding of the strip 115 can be achieved. In this example, the winder box 110 can adapt to, for example, a strip stroke of 100 millimeters to change the circumference. Additionally or alternatively, an additional range can be achieved by changing the total length of the strip to produce a winder box 110 of various sizes (such as small, medium, large and extra large). An advantage of this size design is that the winder box 110 can allow significant changes in the patient's limb size and further significant changes in the ankle circumference due to the presence of edema or swelling. This can reduce the difficulty of determining the device size and matching for a specific patient, and can adapt to the large circumference limbs experienced by lymphedema patients. This reduces or eliminates the need for the size of the specific individual customized strip 115, and simplifies the size matching process.

[0069] This configuration allows for at least two types of measurements. The first type is a relative measurement that quantifies only the change in circumference associated with the change in the reel from its original position due to expansion and contraction of the limb. The second type of measurement is an absolute measurement that can determine the total circumference of the limb by combining the relative measurement, the length of the electronics assembly 105, the fastener 120, and the unused length of the strap 115.

[0070] In the current example, the strip size magnet 335 in the winder box 110 can communicate with one or more strip size magnetic sensors 245 in the electronics subassembly 215. Several strip size magnetic sensors 245 can be positioned so that multiple strip sizes are identified by the relative position and orientation of the magnetic field generated by the strip size magnet 335. In at least one embodiment, up to four strip sizes can be identified using a single strip size magnet 335.

[0071] The strip size magnetic sensor 245 can identify the presence and / or orientation of the strip size magnet 335 in the winder box 110. In some embodiments, two strip size magnetic sensors 245 (such as Hall effect sensors) can each output a signal in the presence of a north pole field, or output different signals in the presence of a south pole field. Through the arrangement of the relative positions of the strip size magnetic sensors 245 and the orientation of the strip size magnet 335 in the winder box 110, five orientation states can be detected and communicated. For example, when no magnetic field is sensed, the winder box 110 is determined (e.g., decoded) as not present; when the magnetic field axis is perpendicular to the circuit board supporting the strip size magnetic sensor 245, a north-north or south-south state can be sensed; and when the magnetic field axis is parallel to the axis along the strip size magnetic sensor 245, a north-south or south-north state can be sensed. Using the strip size magnet 335 and the strip size magnetic sensor 245 in combination to sense the presence or absence of the winder box 110 can allow for identification of removal and replacement events. Additionally, the orientation of the sensing strip size magnet 335 helps identify the size, such as small, medium, large, and extra large, of the winder cassette 110. Winder cassettes 110 of different strip 115 lengths can be constructed to orient the strip size magnet 335 so that the field presented to the strip size magnetic sensor 245 in terms of strength or field orientation can be read by the circuit and interpreted as conveying the size of the winder cassette 110 attached to the measurement assembly 105.

[0072] In some embodiments, the winder box frame 330 and the reel 320 are 3D printed from materials such as Siraya Tech Blu resin and Siraya Tech Blu mecha nylon resin by a mask stereolithography (MSLA) process. The spring 315 can be a 125 mm long × 10 mm wide × 0.025 mm (0.001 inch) all-hard stainless steel shim (Precision Brands, Downers Grove, IL). The angle magnetic sensor 240 can be a giant magnetoresistor angle sensor, such as the AAT101-10E full-bridge angle sensor from NVE, Eden Prairie, MN. The strip size magnetic sensor 245 can be a dual output unipolar Hall effect switch, such as the AH1389 from Diodes, Plano, TX. Magnets 325 and 335 are neodymium available from various suppliers.

[0073] Figure 4 is a top view of the winder cassette 110 relative to the strap 115 and the fastener 120. From this view 400, a partial section AA of the winder cassette 110 is located.

[0074] Figure 5 The winder box 110 is in the assembled state. Figure 4 Partial section view AA.

[0075] In some examples, for example, the capture feature 340 may include a pin 344 that is fixed within the winder box frame 330, such as one or more tabs, grooves or holes in the winder box frame wall for receiving the corresponding ends of the pin, or fixed within an extension extending from one or both walls to mount the hollow end portion of the pin. In some embodiments, one or both ends of the pin 344 may be extruded from or fixed to one or more walls. In such an embodiment, the spring 315 may be attached to the capture feature 340 by, for example, inserting one end of the spring 315 into a gap in the pin 344 of the capture feature 340 mounted to the winder box frame 330 and wrapping or bending the spring 315 around the pin.

[0076] For example, the coil spring 315 can have a narrow wire or wide band configuration. To help secure the spring 315 to the capture feature 340 of the winder box frame 330, the end of the spring 315 inserted into the gap can be wrapped or bent to at least partially wrap around the pin 344. The bent configuration 520 consisting of two bends in the spring 315 can engage the capture feature 340, such as Figure 5 As shown. The distal end of the spring 315 can be connected to the reel 320 by an adhesive 510. The reel 320 can in turn be attached to the strip 115 by an adhesive 505. No limitation to a particular type of fixation or adhesive should be inferred. This transmits the spring 315 force from the capture feature 340 in the winder box frame 330 through the curved configuration 520 of the spring 315. The winder box frame 330 is attached to the spring 315, the spring adheres 510 to the reel 320, and the reel in turn adheres 505 to the strip 115, thereby tensioning the assembly. The action of rotating the angle magnet 325 relative to the angle magnetic sensor 240 as the limb expands and contracts can be achieved using this tensioning mechanism.

[0077] Figure 6 6 is a side view of a device, which may correspond to device 100. In practice, device 100 may drift to its operable, repeatable initial position on the limb due to the effects of gravity and patient movement, such as due to friction between strap 115 and the limb.

[0078] Figure 7 It is taken along line BB Figure 6A detailed cross-sectional view 700 of the measurement assembly 105, winder box 110, strap 115, and fastener 120 of the example device is shown. This demonstrates the engaged use position of fastener 120 with battery drawer 205 and the position of battery 210 in housing 235. The 3:1 scale is indicated to give a sense of the size of the device that may correspond to device 100. However, the scale will vary depending on the size of the figure presented on the page. That is, zooming in or out will affect the scale, and therefore 3:1 should not be considered limiting.

[0079] exist Figure 7 The winder box frame 330, the spool 320, the spring 315, the angle magnet 325 and the strip size magnet 335 work together to determine the rotation of the spool 320, the presence of the winder box 110 and the total length measured around the circumference of the wearer's limb, as described elsewhere herein.

[0080] Figure 8 is an isometric view of a device that may correspond to Figure 1 The device shown in the figure has the housing of the measurement assembly removed. The view orientation shows the electronics in close proximity to the limb with the rear housing 235 removed. There may be components on the electronics subassembly 215 for sensing physiological parameters such as heart rate, SPO2, NIBP, etc. In the example shown, a light emitter 815 that can emit green, red, and infrared wavelengths of light is placed in the center and in close proximity to the wearer. The light from the emitter component enters the wearer's skin. Some of this light is reflected back and sensed by the detector components 805 and 810. The returned light is sensed and evaluated by software. The raw measurement or the evaluated measurement can then be transmitted to other computing devices.

[0081] In some embodiments, the device 100 can use the orientation information detected by the accelerometer to detect when the patient is in a supine position or resting. The resting heart rate is sampled. It is known that changes in resting heart rate vary with patient fluid retention. These heart rate readings can be used to increase confidence in the interpretation of the circumference measurement.

[0082] Limb circumference measurements and limb orientation data may be continuously acquired at regular intervals and processed to produce a personal daily swelling pattern for the subject wearing the device. The daily swelling pattern is characterized by a minimum limb circumference occurring when the subject is lying down, and a maximum limb circumference after the subject has been in an upright position (such as standing or sitting) for a period of time specific to the individual.

[0083] The trend of fluid gain or loss can be calculated over a specified time period (e.g., days, weeks, or months). Fluid gain / loss and fluid gain / loss trends can be compared to thresholds to identify conditions of concern. The system takes specific actions for conditions of concern, including sending messages and alerts to the user and support personnel (e.g., family caregivers, chronic care managers, and / or clinical staff).

[0084] The rate at which body fluid redistributes itself in the body as it rises to a vertical orientation can indicate the viscosity of the interstitial fluid; changes in viscosity are known to be associated with decompensation of heart failure due to changes in protein levels in the interstitial fluid. This is typically assessed by a physician pressing a finger firmly against the patient's ankle and observing whether the resulting "indentation" rebounds quickly. If the indentation rebounds slowly, the condition is described as pitting edema. This is an important medical sign and a useful part of the diagnostic method to characterize the patient's condition.

[0085] The disclosed technology can characterize the rate of change of redistribution of interstitial fluid. By taking multiple measurements as the patient moves from a supine orientation to an upright orientation (typically in the morning), the time required for interstitial fluid redistribution associated with changes in the direction of gravity can be tracked. This rate of change measurement is directly related to the viscosity of the interstitial fluid. Being able to identify interstitial fluid viscosity and changes associated therewith can further inform medical practitioners or computational algorithms of changes in a patient's disease state, as body fluid viscosity provides insight into the root causes of body fluid load (e.g., changes in protein levels in the interstitial fluid).

[0086] Fig. 9 A graph 900 of normal swelling (e.g., limb swelling) for a hypothetical heart failure patient over a 12-day period is shown. Reference numeral 905 is associated with a graph of circumference readings captured by a device (e.g., device 100) versus time, and illustrates a repeated daily swelling pattern over 12 days. Reference numeral 910 is associated with a rolling average of ankle circumference. In some embodiments, an exponential moving average may be used. Reference numeral 915 is associated with a user's normal baseline circumference, which in the example of a heart failure patient is derived from circumference readings measured during a normal or "dry" state of the user.

[0087] Taking into account the minimum and maximum circumferences associated with the swelling pattern, the swelling pattern can be represented by an "average" circumference.

[0088] A baseline swelling pattern or baseline average swelling is identified as the daily swelling pattern or average daily swelling detected when the subject is in a normal healthy state (often referred to as a "dry" state for heart failure patients). The system can calculate or adjust the normal baseline during the use period. The system maintains a normal baseline for comparison to calculate fluid gain / loss.

[0089] Fig.10 An 8-day graph 1000 of a hypothetical heart failure patient's compensatory swelling event (e.g., ankle swelling) associated with fluid retention associated with increased salt intake is shown. Reference numeral 1005 is associated with a graph of circumference readings captured by a device (e.g., device 100) relative to time. Reference numeral 1010 is associated with a rolling average of ankle circumference. A similar graph can be drawn if an exponential moving average is used. Reference numeral 1015 is associated with the patient's normal baseline circumference, which, in the case of a heart failure patient, is derived from circumference readings, such as circumference readings measured during the user's normal or "dry" state. Reference numeral 1020 shows a deviation from a daily swelling pattern that may be associated with the patient's fluid retention, in which case a high-salt diet is consumed for two consecutive days. Reference numeral 1025 points to a corresponding change in average circumference that occurs during a swelling event. Reference numeral 1030 points to a return to normal swelling as the patient's body compensates and eliminates excess fluid within a few days after the event.

[0090] exist Fig.10 In the example above, the waveforms of the individual measurements vary widely 1005. The patterns vary between individuals and days; this individual's pattern is clearly less regular than the previous example. However, the moving average trend line 1025 indicates that the swelling increased by 4 mm over a 2-day period. This coincides with a high-salt meal. The swelling subsides over time 1030 as the body compensates for this infusion.

[0091] Fig.11A graph 1100 is shown of a hypothetical episode of decompensated fluid retention (such as one prior to hospitalization for heart failure). Reference numeral 1105 is associated with a graph of circumference readings captured by a device (e.g., device 100) over a four-week period relative to time. Reference numeral 1110 is associated with a rolling average of ankle circumference. A similar graph can be plotted using an exponential moving average. Reference numeral 1115 is associated with the patient's normal baseline circumference, which in the case of a heart failure patient is derived from circumference readings measured during the user's normal or "dry" state. Reference numeral 1120 shows a deviation from a daily swelling pattern that may be associated with fluid retention, in this case, a trend associated with decompensation associated with a condition requiring clinical intervention. Reference numeral 1125 is the corresponding change in average circumference associated with increased fluid retention.

[0092] Fig.11 Graph 1100 of shows another different measurement pattern. The deviation in circumference measurement can exceed 10 mm in a day, and a change in the average daily swelling signal of several millimeters is a signal of concern. The potential error of the measurement that deviates from the arithmetical processing is larger than the signal for a single measurement. The range of daily measurements for this patient is much larger 1105, and the monthly deviation also increases significantly. The range of swelling in one month is 17 mm at essentially the same location on the same ankle. Interestingly, during the initial two-week period, the average swelling remained within a range of plus or minus 1 mm 1110. However, during the subsequent two-week period, the average daily swelling increased to nearly 6 mm 1125 above the nominal baseline 1115. This represents a substantial and sustained trend in the circumference data indicating an increase in the patient's fluid volume.

[0093] This ongoing trend can be compared with the individual patient's medical history and patients who may have similar characteristics, such as, but not limited to, age, height, weight, left ventricular ejection fraction, comorbidities, and / or similar metrics. In addition, other physiological metrics such as, but not limited to, heart rate, SpO2, NIBP, body temperature, fall shock, gait, arrhythmia, tachycardia, bradycardia, atrial fibrillation, and / or heart rate variability may also be considered in conjunction with these measurements. Processing this information using appropriate correlation algorithms can achieve real-time, consistent, continuous, and / or immediate acute assessment of the severity of trend events and predict the likelihood of an impending decompensation event. In some embodiments, trained machine learning models or rule application algorithms can be utilized and updated based on feedback (human or machine) from patient experience and / or from a patient population to continuously improve the accuracy of these predictions; the more measurements are taken; the more accurate the predictions, especially to minimize interpolation errors and determine an accurate model of daily changes in limb swelling. When a substantial swelling event is detected that exceeds a predetermined threshold stored on the device or stored remotely, the patient or their caregiver can be notified to take action to change the patient's overall activity, contact their medical provider, change the amount of treatment (such as diuretics), add or subtract other medications, or implement other methods that may change the course of the disease. In some examples, the responsive action is provided urgently; in other examples, such as dietary changes, the responsive action may be a suggestion or instruction. Changes in medication dosages typically follow a predefined treatment plan from the patient's physician, where, for example, an additional diuretic dose may be required when the patient experiences a substantial swelling event.

[0094] Given the small size of the mathematically processed signal of interest compared to the range of circumference measurements over a single day, it is desirable to minimize potential, continuously varying physiological distortions caused by the sampling rate. Linear interpolation that truncates the actual limb swelling offset values ​​can substantially alter the value of the calculated signal of interest. In the simplest example, a plot of circumference measurements at random times during a week may produce significantly different results that may be substantially inconsistent with the same patient and condition sampled more densely. This is particularly true when evaluating the rate of change of circumference associated with changes in the patient's gravitational orientation.

[0095] exist Fig. 9 , Fig.10 and Fig.11 In the non-limiting example shown, measurements are taken every 10 minutes, but it should be understood that different time intervals are within the scope of the present disclosure.

[0096] These individual measurements can be mathematically aggregated over a period of time, such as a day, 48 hours, or any period of time suitable for monitoring and analysis. In this example, the mathematical aggregation is by means of a rolling average; exponential moving averages are also considered. A series of these aggregated measurements are then compared to look for evidence of deviation or excursion. Fig. 9 In the example of , for example, there is a series of points representing individual circumference measurements. It should be noted that there is considerable variability in these measurements.

[0097] Depending on the date and time, the measurements for the same location on the same ankle for this individual ranged by 10 millimeters. But the overall daily oscillation in the measurements is actually quite stable. As can be seen in the average daily circumference trendline 915, the range for this individual is about one millimeter.

[0098] Described herein is a method for collecting multiple measurements of minimum limb circumference at a typical limb narrowing at the ankle or wrist, for example, noting that the teachings herein apply regardless of whether the minimum limb circumference is at a narrow point or point of narrowing or at a location on a constant circumference (such as a constant cylinder). Moreover, limb circumference is closely related to interstitial fluid volume. Moreover, interstitial fluid volume is a key medical concern for patients with conditions such as decompensated heart failure, renal function, and similar physiological conditions. Increases in interstitial fluid volume are associated with decompensated heart failure. From Fig. 9 , Fig.10 and Fig.11 It is clear that a single measurement (perhaps at a doctor’s appointment) will yield wildly different and conflicting results depending on the random time of day that the appointment is taken. This limits doctors to a rough estimate of the presence or absence of swelling, such as pressing their fingers onto your ankle. The lack of a practical and rigorous medical measurement limits the usefulness of this physiological parameter. Changes in fluid volume (which are relevant physiological information) are evident over time through careful quantification and tracking. Average changes of a few millimeters can appear as important signs of disease progression, but are not visible in a single exam or daily examination and require more precise measurements than might be obtained through visual inspection alone.

[0099] It should be noted that taking a single measurement at a fixed time of day will not reliably produce accurate results. Fig. 9 , Fig.10 and Fig.11 As can be seen in Figure 2, extreme excursions in the measurements do not necessarily occur at the same time every day.

[0100] Fig.12An example of a circuit 1200 is shown that demonstrates the efficacy of integrating interstitial fluid volume monitoring via the device 100 with determined results that can be automatically followed according to the techniques and concepts described herein. That is, the absolute measurements of the device 100 and / or the trend of these measurements over time (navigation) can be output as an alert (e.g., discrete data, waveforms, and / or simple notifications) for clinical evaluation 1202 by humans or artificial intelligence based on, for example, machine learning principles (guidance). The results of the clinical evaluation 1202 can be output as a treatment plan (which can include, among other things, recommendations or instructions for the patient, medication or treatment prescriptions, etc.), and optionally entered into a treatment log 1204 (controls). The circuit 1200 can end with the analysis of the patient's response to the treatment plan, completing the patient-supported navigation-guidance-control integration enabled by the device 100 and its operation / function of monitoring and / or measuring swelling, and what is obtained from it is not simply data for evaluation, but real-time monitoring to take action, avoiding the need for many consultations or interventions that were previously generally considered best or even necessary practices.

[0101] Fig.13 Graph 1300 shows an example of an integrated medication log and ankle circumference history. The graph allows the practicing physician to determine the outcomes associated with the prescribed treatment plan. The circumference information can be used in conjunction with the prescribed treatment plan to determine if the medication is achieving the desired outcome, and the medication can be adjusted as necessary to achieve the desired outcome. Average circumference 1305 is the patient's response to the medical treatment plan 1315. The physician evaluates the response to determine effectiveness, and makes adjustments to the treatment plan 1315 to achieve the desired outcome. The non-invasive blood pressure curve 1320 can be used to assess the patient's tolerance for medication adjustments that can reduce fluid retention while maintaining blood pressure within an allowable range.

[0102] Fig.14 An example architecture 1400 is shown implementing monitoring of changes in volume and properties of interstitial fluid in a patient 1402. The illustrated architecture 1400 includes a device 1404, a health care entity 1406, a personal contact 1408, and a wireless access point 1410, but this is merely an example and other configurations including more or fewer components are contemplated.

[0103] Health care entities 1406 may include, but are not limited to, medical facilities, caregivers, and / or other personnel associated with patient care. Caregivers or other personnel may operate one or more computing devices as part of their care functions.

[0104] The personal contacts 1408 may include support personnel operating one or more computing devices connected to the database server 1412 via a wired or wireless communication link (e.g., the Internet or other wireless and / or wired connection) using SMS messaging, WIFI protocols, Bluetooth protocols, etc. The personal contacts 1408 may also include a patient's personal representative, family members, or other individuals configured to receive information exported from the device 100.

[0105] The control system may include a database server 1412 connected to a database 1414. The database 1414 may store relevant data about the patient 1402 (such as patient history, patient records, etc.), trigger event levels, and addresses to which messages (e.g., notifications, alarms, etc.) are to be sent.

[0106] Depending on implementation details, information from device 1404 can travel several alternative paths. For example, the information can be entered into a computing device (e.g., a patient desktop computer, a patient cell phone, a patient portable computer, etc.) connected to a database server 1412 (or web server) via the Internet, a cellular gateway, or other network. The computing device can transmit the feedback information to the database server 1412 directly or via access point 1410. Device 1404 can communicate device messages to the computing device for transmission to the database server 1412.

[0107] The device 1404 may continuously measure position measurements and store these position measurements on the device itself or remotely (e.g., at a database 1414) at a predefined frequency. These positions may be interpreted as relative circumference measurements when compared to any reference, or as absolute circumference measurements when combined with dimensional information that establishes a relationship between the position of the reel 320 and a known circumference.

[0108] Fig.15 Various components of the measurement component 1505 are shown, arranged according to one or more embodiments described herein. For example, the measurement component 1505 may correspond to Figure 1 The measurement assembly 105 shown. In the illustrated example, the measurement assembly 1505 can be configured to measure the circumference of a limb by detecting the extension or retraction of a strap 115 attached to a winder box 110 coupled to the measurement assembly 1505 using one or more sensors, such as magnetic sensors.

[0109] like Fig.15 As shown, the measurement component 1505 may include one or more of a communication interface 1502 , a user interface 1504 , one or more processors 1506 , one or more magnetic sensors 1508 , a memory 1510 , and device hardware 1512 .

[0110] The communication interface 1502 may include wireless and / or wired communication components that enable the measurement component 1505 to communicate with the measurement component 1505 via a communication network (such as reference Fig.14 The communication network described herein transmits data to and receives data from other networked devices.

[0111] The user interface 1504 can enable a user to provide input and receive output from the measurement component 1505, including, for example, providing one or more inputs to initiate device activation and / or set metadata, tags, communication parameters, monitoring parameters, etc. The user interface 1504 may include a data output device (e.g., a visual display, an audio speaker) and one or more data input devices. The data input device may include, but is not limited to, a combination of one or more of a touch screen, a physical button, a camera, a fingerprint reader, a keypad, a keyboard, a mouse device, a microphone, a voice recognition package, and any other suitable device or other electronic / software selection method.

[0112] The processor 1506 and the memory 1510 may implement an operating system. The operating system may include components that enable the measurement component 1505 to receive and transmit data via various interfaces (e.g., user interface 1504, communication interface 1502, and / or memory input / output devices) and process the data using the processor 1506 to generate output. The operating system may include a display component that presents the output (e.g., displaying the data on an electronic display, storing the data in a memory, transmitting the data to another electronic device, etc.). In addition, the operating system may include other components that perform various additional functions typically associated with an operating system.

[0113] Magnetic sensor 1508 can be configured and located within the housing of a wearable device of the type described herein, working with electromagnetic circuitry to detect an amount of rotation of the magnet associated with the winding and unwinding of strap 115, which corresponds to the circumference of the limb.

[0114] The memory 1510 can be implemented using a computer-readable medium such as a computer storage medium. Computer-readable media include at least two types of computer-readable media, namely computer storage media and communication media. Computer storage media include volatile and non-volatile, removable and non-removable media implemented by any method or technology for storing information (such as computer-readable instructions, data structures, program modules or other data). Computer storage media include, but are not limited to, random access memory (RAM), dynamic random access memory (DRAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technology, CD-ROM, digital versatile disk (DVD) or other optical storage, cassettes, magnetic tapes, disk storage or other magnetic storage devices, or any other non-transmission medium that can be used to store information for access by a computing device. Computer-readable storage media are not composed of modulated data signals (such as carrier waves) and are not completely formed by modulated data signals. In contrast, communication media can embody computer-readable instructions, data structures, program modules or other data in modulated data signals, such as carrier waves or other transmission mechanisms.

[0115] The memory 1510 may include an operating system, device software 1514, and one or more applications 1516, as well as data collected by the magnetic sensor 1508 or input by a user or received from a remote source. The applications 1516 may include any application software executable by the one or more processors 1506, including, for example, but not limited to, applications that facilitate the functionality of the wearable device 1505 for detecting extension and retraction of the strap 115 by detecting and processing the magnetic field of the magnet within the reel 320 and data derived therefrom; manipulation, formatting, addition, deletion, or modification of metadata; and image or data processing.

[0116] Device software 1516 may include software components that enable measurement component 1505 to perform functions. For example, device software 1516 may include a basic input / output system (BIOS), a boot ROM, or a boot loader that starts measurement component 1505 and executes an operating system after measurement component 1505 is powered on.

[0117] The device software 1516 may include software components that calculate relative times associated with data collection, which can be resolved to actual times within other computer systems synchronized with a universal time reference.

[0118] Device hardware 1512 may include additional hardware that facilitates performing user interface 1504, data display, data communications, data storage, and / or other device functions.

[0119] Fig.16 Shown Fig.14 14. The database server 1412 may include a communication interface 1602, one or more processors 1604, a memory 1606, and hardware 1608. As with the communication interface 1502 of the measurement component 1505, the communication interface 1602 may include wireless and / or wired communication components that enable the database server 1412 to communicate with the measurement component 1505 via a communication network (e.g., reference Fig.14 The communication network described herein transmits data to and receives data from the measurement component 1505 and other networked devices.

[0120] The processor 1604 and the memory 1606 may implement an operating system. The operating system may include components that enable the database server 1412 to receive and transmit data via various interfaces (e.g., the communication interface 1602 and / or memory input / output devices) and process the data using the processor 1604 to generate output. The operating system may include a display component that presents the output (e.g., displays the data on an electronic display, stores the data in a memory, transmits the data to another electronic device, etc.). In addition, the operating system may include other components that perform various additional functions typically associated with an operating system.

[0121] The memory 1606 may include an operating system, device software, and one or more applications, as well as data collected by the magnetic sensor 1508 or input by the user or received from a remote source. The application may include any application software executable by the one or more processors 1604, including but not limited to applications that train and / or execute rules or machine learning models and algorithms 1610 to process data received from the measurement component 1505, including generating waveforms of circumference changes, interpreting data, applying activity information, subject medical history, medication treatment plan and other data, generating predictive outputs for analysis and / or responding to feedback to update or retrain models, etc.

[0122] Hardware 1608 may include additional hardware to facilitate performing data display, data communications, data storage, and / or other device functions.

[0123] Fig.17is a flow chart of an example process 1700 that may be performed, at least in part, by the measurement component 105 for measuring the limb circumference of a subject, generating a waveform of the measurements over time, and outputting an indication of the condition exposed by the waveform. The process 1700 is presented as a collection of boxes in a logical flow chart that represents a sequence of operations that may be implemented in hardware, software, or a combination thereof. In the context of software, a box represents a computer-executable instruction that performs the enumerated operations when executed by one or more processors. In general, computer-executable instructions may include routines, programs, objects, components, data structures, etc. that perform specific functions or implement specific abstract data types. The order in which the operations are described is not intended to be construed as a limitation, and any number of the boxes may be combined in any order and / or in parallel to implement the process. For purposes of discussion, reference is made to FIG. Figure 1 Apparatus 100 is shown to describe these processes.

[0124] At block 1702, the device 100 can measure the circumference of the limb at a repeatable initial position over a period of time as an indicator of the volume of interstitial fluid in the limb. In some embodiments, the device 100 can be applied to a limb of a human subject and allowed to move to settle into a repeatable initial position on the limb. In one or more embodiments, the repeatable initial position can be the minimum circumference of the limb where the band tension balances the interstitial fluid pressure to enable the device to perform the above-mentioned measurement.

[0125] At block 1704, the device 100 may generate a waveform showing the change in current circumference data derived from the measured circumference over time. In some embodiments, circumference measurements may be performed periodically (e.g., once a day), intermittently (e.g., manually initiated), or continuously. In some embodiments, some or all of the data processing and waveform generation may be performed off-device, such as by a remote computing device.

[0126] At block 1706, device 100 may compare the waveform to the waveform of the subject's baseline circumference data at a repeatable initial position. The difference in the waveform may be interpreted by device 105, transmitted to an off-device or remote location (such as a doctor's office, mobile device, portable computer, etc.), or interpreted by a human.

[0127] At block 1708, device 100 may output the results of the comparison and an indication of exposure through the comparison. For example, if the waveform of the current circumference measurement shows an increase over the subject's baseline waveform, an alert may be displayed on measurement component 105, transmitted to a mobile device or a more remote endpoint. In addition, or in the alternative, instructions may be output, such as to advise the subject to make changes in diet or exercise, review therapy, or make specific adjustments to therapy (including medication dosage adjustments), and the like.

[0128] Figures 18 to 26 An example of another apparatus is shown. Aspects of the apparatus similar to aspects of apparatus 100 are indicated by similar reference numerals, except for the initial characters (e.g., Fig.18 The device 1800 shown may correspond to Figure 1 The device 100 shown).

[0129] Fig.18 An isometric view of a device 1800 that can be configured to monitor changes in volume and properties of interstitial fluid in a human body is shown as another example. Device 1800 can include, among other components, a device assembly that includes a measurement assembly 1805, a winder box 1810, a strap 1815 configured to be placed around a subject's limb, and a buckle 1820. As with device 100, the subject can wear device 1800 around the lower arm (i.e., below the elbow) or calf (i.e., below the knee), but the teachings herein can be applied to other body parts, particularly body parts with axial portions, and therefore should not be considered limited except by the type of data required and the location where the data may be obtained.

[0130] The measurement assembly 1805 can house an electronics subassembly to obtain data and communicate the data or information based on the data. The electronics subassembly described below can include a sensor and associated electronics that, in some embodiments, can perform an analysis of the sensor data and output results of the analysis and / or recommendations or instructions based on the results. In some embodiments, the electronics subassembly can include a sensor portion that includes one or more magnetic sensors positioned relative to one or more corresponding magnets on the winder box 1810, as described more fully below.

[0131] Winder box 1810 typically cooperates with strap 1815 to achieve a loosely tensioned but snug fit to the limb even in the presence of severe swelling. As with device 100, device 1800 typically does not fit tightly to the limb even in the presence of severe swelling. To this end, strap 1815 and winder box 1810 are configured so that strap 1815 can extend and retract as the limb swells and contracts, thereby enabling a substantially constant force to be applied to the limb. In some embodiments, winder box 1810 in combination with strap 1815 and fastener 1820 can be a replaceable component that can be easily replaced by the user if the winder box becomes dirty or broken.

[0132] Fig.19 Shown with Fig.18An exploded view of an example measurement assembly 1805, winder box 1810, strip 1815, and buckle 1820 of the illustrated example corresponding device 1900. The housing 1935 and cover 1905 are configured to house a battery 1910; an electronics subassembly 1915 including a radio module 1920, an angle magnetic sensor 1940, and one or more strip size magnetic sensors 1945; an insulator 1925, and a gasket 1930. The measurement assembly 1805 can be substantially fluid-tight to prevent the ingress of bodily fluids.

[0133] Battery 1910 can be similar to battery 210. In some examples, battery 1910 can be captured between electronics subassembly 1915 and the top of housing 1935. In some embodiments, another portable power source can be used, such as a rechargeable battery, a fuel cell, a storage capacitor, energy harvested from the patient, energy harvested from the environment, etc.

[0134] Insulator 1925 can be an electrical insulator and thus can be positioned to insulate battery 1910 from electronics subassembly 1915 so that battery 1910 can be replaced without contacting electronics subassembly 1915 or any components or wiring on the electronics board substrate. In some embodiments, insulator 1925 can be embossed or printed with configuration information for device 1900 or any of its components, such as a version.

[0135] Similar to the electronics subassembly 215, the electronics subassembly 1915 can be a printed circuit board and includes electronic components that control and perform one or more of the limb circumference sensing. The limb circumference can be used by the onboard control system or transmitted to a remote computing device, which runs an algorithm on the data from the sensed limb circumference, outputs a message, and generates a graphical result showing the measurement value over time, which can be interpreted by a medical professional (for example) to gain insight into the current condition of the patient wearing the device 1900. In some embodiments, the electronic components may include one or more magnetic sensors (such as magnetic sensors 1940, 1945), one or more optical sensors, one or more processors, memory, and accelerometers. The memory can store instructions that, when executed by one or more processors, cause one or more processors to perform various operations described herein. In at least some embodiments, the magnetic sensor can detect the limb circumference. In at least some embodiments, the accelerometer can detect the orientation and movement of the patient and output data that can be used by the onboard control system or transmitted to the remote computing device to determine the patient's activity level. For example, using information received from an accelerometer, the device can detect, accumulate, store and / or transmit accelerometer measurements at a sufficiently high frequency and correlate that information with circumference readings to provide an adequate representation of the effects of gravity on the limb and limb activity during the time between circumference measurements.

[0136] As with radio module 220, radio module 1920 can transmit digital or analog signals (e.g., containing patient motion information) to an external device. For example, the signal can be transmitted to a nearby computer, smart phone, tablet computer, etc., which has the processing capability to receive the signal, analyze the data provided by the signal, output instructions or commands, and / or relay the signal to a remote computing device such as a server, computer, or database (e.g., in a doctor's office or data center).

[0137] Gasket 1930 is configured and positioned to seal housing 1935 and prevent the intrusion of dust or water that could damage sensitive components inside. For example, gasket 1930 can be positioned between housing 1935 and cover 1905. Gasket 1930 includes, but is not limited to, insulating materials suitable for its purpose. In at least one embodiment, gasket 1930 can be solid rather than annular as disclosed in the example of gasket 230. In the case of gasket 1930 depicted, gasket 1930 and cover 1905 can have flat surfaces and large tolerances to match the opening of housing 1935.

[0138] As with the measurement module 105, the measurement assembly 1805 can be configured so that the insulator 1925 and the electronics subassembly 1915 including the radio module 1920 are inserted into the housing 1935. The cover 1905 can be coupled with a gasket 1930 positioned at the location where the cover 1905 meets the housing 1935 by a snap fit to facilitate easy removal of the cover 1905 to replace the battery 1910. In this configuration, the cover 1905 can be snapped into the housing 1935, thereby compressing the gasket 1930, which seals the interior of the housing 1935 to prevent dust or water intrusion. The winder box 1810 can then be assembled to the measurement assembly 1805 with the aid of a stopper that holds the measurement assembly 1805 and the winder box 1810 (including the strip 1815) together.

[0139] The distal end of the strip 1815 passes through the body of the fastener 1820 and is secured by adhering the strip 1815 to itself by heat bonding the end to the body of the strip 1815 with an adhesive material. However, it should be understood that many other methods of bonding, such as bonding the material of the strip 1815 to itself, fasteners 1820, crimping, and the like, are within the scope of the present disclosure.

[0140] Similar to clasp 120, clasp 1820 may be coupled to electronics subassembly 1915 via latching features that engage the geometry of cover 1905 in electronics subassembly 1915 to wrap around a limb.

[0141] As in the case of winder case 110, winder case 1910 can be configured to accommodate straps 1915 of varying lengths, thereby allowing device 1900 to accommodate a wide range of applications, from a small wrist to a significantly swollen leg, for example.

[0142] In some embodiments, the housing 1935, cover 1905, and / or fastener 1820 can be 3D printed from materials such as Siraya Tech Blu resin and Siraya Tech Blu mecha nylon resin using a mask stereolithography (MSLA) process. The gasket 1930 can include Poron (polyurethane foam). The strap 1815 is generally flexible and inelastic and can be made of a biocompatible porous material for patient comfort. As an example, the material can be an open weave, 80 threads per inch polyester fiber with a fused edge, 0.008" Teslin (PPG, Barberton, OH) or Tyvek (Wilmington, DL), or a non-woven open fabric such as an embroidery stabilizer.

[0143] Fig. 20An exploded view of the winder box 1810, the strip 1815, and the buckle 1820 that remain when the measurement assembly 1805 is removed in some embodiments is shown. The winder box 1810 can include a winder box frame 2030, a spring 2015, and a reel 2020. The winder box frame 2030 can include a capture feature 2040 to receive a strip size magnet 2035. The winder box frame 2030 can be configured to receive a drive pin 2044. The drive pin 2044 can include a drive pin feature 2042 (e.g., a protrusion or a configuration for receiving a protrusion) that is configured to be coupled to a corresponding feature in the winder box frame 2030 (such as a configuration for receiving a protrusion of the drive pin feature 2042 or a protrusion corresponding to the receiving configuration of the drive pin feature 2042). The reel 2020 can be cylindrical and include an angle magnet 2025. The strip 1815 can be wound on the reel 2020 when installed in the winder box frame 2030, as described below. In some embodiments, the winder box 1810, the strip 1815 and / or the buckle 1820 can be replaced individually or as a combination including any two or all three.

[0144] The spring 2015 may be a spiral metal foil having a hole 2050 disposed at a portion thereof, which is engaged with the spiral metal foil when the drive pin 2044 is inserted into the coil spring 2015. Fig. 20 The spring coupler formed by the protrusion 2045 on the drive pin 2044 shown. Another part of the spring 2015 can have a hole 2055 that hooks into the spring coupler formed by the drive pin 2044. Fig. 20 The projection 2060 in the illustrated reel 2020 forms another spring coupler to allow the spring 2015 to wind and provide tension when the strap 1815 is stretched. The spring 2015 can provide a substantially constant spring force load (e.g., approximately 10 grams to 40 grams) that is sufficient to hold the strap 1815 snugly to the limb without unnecessary, uncomfortable pressure.

[0145] The strip 1815 is attached to and wound on the spool 2020. An angle magnet 2025 may be pressed or otherwise fitted into an opening, gap, or recess of the spool 2020 such that it is opposite to the angle magnetic sensor 1940 on the electronics subassembly 1915. A strip size magnet 2035 may be pressed or otherwise fitted into an opening, gap, or recess of the winder cassette frame 2030 such that it is opposite to one or more of the strip size magnetic sensors 1945 on the electronics subassembly 1915 of the measurement assembly 1805. The magnetic sensors 1940 and 1945 are configured and positioned to sense the magnetic fields of the magnets 2025 and 2035 through the housing 1935.

[0146] The action of increasing and decreasing the length of the strip 1815 as the limb expands and contracts can be accomplished by a tensioning mechanism that includes a spring 2015 within a winder box frame 2030 and a reel 2020 that can accommodate a portion of the length of the strip 1815 wound on the reel 2020. In some embodiments, the spring 2015 can be a constant tension spring. As the limb stretches, the strip 1815 unfolds, thereby increasing the length of the strip 1815 to accommodate the increased circumference of the limb, while maintaining the constant tension of the strip 1815 around the limb by the constant force applied by the spring 2015. The tension of the strip 1815 can be matched with the interstitial fluid pressure and elasticity of the skin, so that the device expands and contracts without producing noticeable indentations in the limb. In this regard, and in conjunction with other embodiments described herein, it should be understood that the constancy of force and tension does not need to be precise, but rather within a reasonable tolerance range that enables the device to perform its function of measuring limb circumference according to the principles outlined in the present disclosure, particularly measuring the difference in limb circumference relative to a baseline or other reference.

[0147] The angle magnet 2025 installed in the reel 2020 can be sensed by the angle magnetic sensor 1940, so that when the winding and unwinding of the strip 1815 causes the reel 2020 to rotate, the degree of rotation of the reel 2020 can be identified by a signal output by the angle magnetic sensor 1940 and received at the electronic device component 1915 electrically connected to the angle magnetic sensor 1940.

[0148] The angular magnetic sensor 1940 can be composed of multiple resistor elements that are arranged to output a set of variable signal strength voltages. In at least one embodiment, these signal strength voltages correspond to the sine and cosine of the degree of rotation of the magnet 2025 field relative to the magnetic sensor 1940. This can be achieved by a full-bridge sensor based on spintronic technology (a suitable sensor currently produced by NVE, Inc. of Eden Prairie, MN) because this produces an extremely low-power configuration that is relatively insensitive to the distance and axial misalignment between the magnet 2025 and the angular magnetic sensor 1940. Since the diameter of the reel 2020 defines a known circumference by the formula C=Pi×D, the diameter can be converted into an accurate change in length measurement when the strip 1815 expands and contracts. The diameter of the reel 2020 can be determined / calibrated when each device is manufactured.

[0149] In addition to measuring the rotation of magnet 2025, the circuit also retains information about the rotation history. In this example, quadrature detection can be implemented in software or hardware to track the current rotation or number of revolutions. In at least one embodiment, quadrature detection can be achieved by using a comparator circuit connected to an interrupt function on the processor. But in other embodiments, dedicated circuit counting and logic components or integrated functions within the processor itself can take on this function. When the strip 1815 is wound around the reel 2020 for more than 360 degrees, the rotation count is maintained. The rotation count together with the current angle measurement enables the software to calculate the total rotation degree. The diameter of the reel 2020 is combined with the total rotation degree, together with the length of the manufacturing strip 1815 when the spring 1815 is not used, to determine the total circumference measurement.

[0150] As above Figure 3 As described in the discussion of , additional considerations may be involved in calculating the total length. As noted above, the strip 1815 changes the effective diameter of the winding portion and the circumference on the reel 2020 as the strip 1815 is wound on the reel 2020, as the layers are stacked. To account for this, the rotational history and manufacturing design of the winder box 1810 can be identified and a diameter change consistent with the thickness of the strip 1815 and the number of turns of the strip material around the reel 2020 is applied.

[0151] The circumference of the limb is equal to the length of the unwound strip 1815 at the starting or retracted position plus the length of the body and fastener 1820 of the measuring assembly 1805, plus the sum of the "variable length" of the strip 1815 that is wound and unwound from the reel 2020 as the limb expands and contracts at the minimum circumference or repeatable position. The variable length of the strip 1815 is equal to the proportional rotation corresponding to the current degree of rotation of the reel 2020 from the original position (defined as 0 degrees) plus the number of complete rotations of the reel from the original position, multiplied by the reel circumference (i.e., the reel diameter multiplied by PI), while taking into account the wound portion of the strip still on the reel. The proportional rotation current angle measured as the number of turns from the original position that have occurred can be calculated based on the arc tangent of the sine / cosine provided by the magnetic sensor / magnet relationship and the quadrant in which it occurred. The original position is captured when the strip is installed in the original position. The number of full rotations can be determined using quadrature detection (considering each 90 degree rotation measured from 0 degrees as one quadrant), in this example the quadrature detection can detect the number of times the reel goes from quadrant 4 to quadrant 1 (see figure below - quadrature plot).

[0152] When the winder box 1810 is manufactured, the length of the strip 1815 is controlled when the spring 2015 is in a relaxed and unused state. If the rotation of the magnet 2025 is consistent with the reference corresponding to the manufactured relaxed orientation, and the rotation history shows no additional winding, and the angle does not appear to be jittered due to wearing, it can be assumed that the device 1900 is not worn. In some embodiments, the spring 2015 can retract the strip 1815 to the original position, which can be read by software that is executed to interpret the signal representing the detected angle of the reel 2020 using an indicator or message output. The detection of these states can also be used to indicate whether the device is worn. In some embodiments, data from the device 1900 in the "not worn" state can be ignored when evaluating the wearer's condition. Further, if this state persists, the patient can be contacted or checked for any problems with the patient wearing the device 1900.

[0153] As with device 100 , device 1900 can accommodate a range of limb sizes in at least two ways, namely by winding the strap 1815 in larger sizes and / or by varying the overall length of the strap to produce winder boxes 1810 of various sizes.

[0154] This configuration allows for at least two types of measurements. The first type is a relative measurement that quantifies only the change in circumference associated with the change in the scroll from its original position due to the expansion and contraction of the limb. The second type of measurement is an absolute measurement that can determine the total circumference of the limb by combining the relative measurement, the length of the electronics assembly 1805, the fastener 1820, and the unused length of the strap 1815.

[0155] In the current example, the strip size magnet 2025 in the winder box 1810 can communicate with one or more strip size magnetic sensors 1945 in the electronics subassembly 1915. Several strip size magnetic sensors 1945 can be positioned so that multiple strip sizes are identified by the relative position and orientation of the magnetic field generated by the strip size magnet 2035. In at least one embodiment, up to four strip sizes can be identified using a single strip size magnet 2035.

[0156] The strip size magnetic sensor 1945 can identify the presence and / or orientation of the strip size magnet 2035 in the winder box 1810. In some embodiments, two strip size magnetic sensors 1945 (such as Hall effect sensors) can each output a signal in the presence of a north pole field, or output different signals in the presence of a south pole field. Through the arrangement of the relative positions of the strip size magnetic sensors 1945 and the orientation of the strip size magnet 2035 in the winder box 1810, five orientation states can be detected and communicated. For example, when no magnetic field is sensed, the winder box 1810 is determined (e.g., decoded) to be absent; when the magnetic field axis is perpendicular to the circuit board supporting the strip size magnetic sensor 1945, a north-north or south-south state can be sensed; and when the magnetic field axis is parallel to the axis along the sensor 1945, a north-south or south-north state can be sensed. Utilizing the strip size magnet 2035 and the strip size magnetic sensor 1945 in combination to sense the presence or absence of the winder box 1810 can allow for identification of removal and replacement events. In addition, sensing the orientation of the strip size magnet 2035 helps to identify the size of the winder box 1810, such as small, medium, large and extra large. Winder boxes 1810 of different strip 1815 lengths can be constructed to orient the strip size magnet 2035 so that the field presented to the strip size magnetic sensor 1945 in terms of strength or field orientation can be read by the circuit and interpreted as conveying the size of the winder box 1810 attached to the measurement assembly 1805.

[0157] In some embodiments, the winder box frame 2030 and the reel 2020 are 3D printed by a mask stereolithography (MSLA) process from materials such as Siraya Tech Blu resin and Siraya Tech Blu mecha nylon resin. The spring 2015 can be a 125 mm long × 10 mm wide × 0.025 mm (0.001 inch) all-hard stainless steel washer (Precision Brands, Downers Grove, IL). The angle magnetic sensor 1940 can be a giant magnetoresistor angle sensor, such as the AAT101-10E full-bridge angle sensor from NVE, Eden Prairie, MN. The strip size magnetic sensor 1945 can be a dual output unipolar Hall effect switch, such as the AH1389 from Diodes, Plano, TX. Magnets 2025 and 2035 are neodymium available from various suppliers.

[0158] Fig.21An example of a digital circuit 2100 is shown that can be implemented to perform quadrature decoding, including detection of revolutions (digital through a 0 degree reference angle) counts in software at a fraction of the power used by some microprocessor quadrature decoder circuits. In such a microprocessor quadrature detection circuit, interrupts can be fed to a microprocessor with quadrature detection that counts rotations, but this requires the microprocessor to remain awake, which uses power. The digital circuit 2100 utilizes interrupts with reduced power usage, combining interrupts with analog angle measurements to track quadrants and thereby accurately count rotations while accounting for jitter at the boundary between two adjacent quadrants. It should be noted that the digital circuit 2100 and / or the measurement techniques described in this regard can be implemented with other embodiments described herein.

[0159] The digital circuit 2100 can trigger an interrupt that can wake up the CPU or trigger additional software components to perform one or more of the actions described herein. In one example, the interrupt rate associated with the rapid extension or retraction of the strip can be used to wake up the processor. In some embodiments, the angle sensor 2105 can generate electrical values ​​corresponding to the sine 2110 and cosine 2115 of the angle of the magnetic field orientation exposed by the angle magnet 2025. The comparator 2120 simplifies the waveform from the angle sensor 2105 (corresponding to the angle magnet sensor 1940) and determines the 0 and 180 degree intersection signals 2125 of the waveform output (corresponding to the boundaries between quadrants Q4-Q1 and Q2-Q3, respectively). These intersection signals 2125 can be electrically connected to the CPU 2130 input pins and can be used by the device 1900 as interrupts to the CPU 2130. These interrupts 2125 can be used to wake up the CPU 2130 from a sleep state to an active state, and can also be used to trigger communication events, such as Bluetooth broadcast conditions or other software components.

[0160] In some embodiments, these cross point signals 2125 can also be used in a low power hybrid digital-to-analog approach to maintain accurate rotation counts when "jitter" may occur (such as when the circuit detects or determines that a full rotation has occurred when the 360 ​​to 0 boundary is crossed).

[0161] The following diagram shows the method used to correctly maintain the rotation count.

[0163] Consider a small range between -1 degrees and +1 degrees from reference 0, calling the left side of 0 the west zone and the right side of 0 the east zone. In this example, the digital 0 degree interrupt sensing area can be called the rotation count area and the analog sensing area can be called the angle area. In this range so close to 0, one or the other of the analog (angle) or digital interrupt (rotation count) sensing may not be consistent. That is, the angle measurement itself may locate the angle in Q4 west of 0, while the digital interrupt that detects or determines the number of revolutions (i.e., the number of times the reference 0 intersection has been passed) may be slightly off and locate the interrupt in Q1 east of 0. If we believe that the rotation count area is correct, an angle correction should be performed. In one example, we can: 1. Track the region via interrupts at both 0 and 180 so that the current region the rotation count is in is known. 2. The area of ​​the angle is defined by 0 --> 1 degree = East and 359 --> 0 = West. 3. Within this ±1 degree, if the zone is determined not to match, then 360 degrees is added or subtracted from the angle measurement in order to match the rotation count zone which has been assumed to be correct. 4. If the rotation count area and the angle area match, the angle measurement value is used as is.

[0164] As mentioned, the rate of the rotation count interrupts can be used to enter broadcast mode. More specifically, low power detection of a rotation crossover combined with the time at which the crossover occurs can be used as a trigger to enter Bluetooth broadcast mode, a similar communication protocol, or other variable portion of the software. In this way, the angle sensor interrupt can be used to perform rotation counting and quickly extend or release the strip, snapping the strip to enter broadcast.

[0165] Fig. 22 is a top view 2200 of the winder box 1810 relative to the strip 1815 and the buckle 1820. From this view, a partial section AA of the winder box 1810 is located.

[0166] Fig.23 The winder box 1810 is in the assembled state. Fig. 22 Partial section view AA.

[0167] In some examples, the capture feature 2045 of the drive pin 2044 can fit within one or more tabs, grooves, or holes in one or more walls or the winder box frame 2030. In some embodiments, one or both ends of the drive pin 2044 can be extruded from or fixed to one or more walls. In such embodiments, the spring 2015 can be attached to the capture feature 2045 mounted to the winder box frame 2030 by, for example, inserting the end 2050 of the spring 2015 into the gap in the drive pin and wrapping or bending the spring 2015 around the drive pin 2044.

[0168] For example, the coil spring 2015 can have a narrow wire or wide band configuration. To help secure the spring 2015 to the capture feature 2040 of the winder box frame 2030, the end of the spring 2015 inserted into the gap can be wrapped or bent to at least partially wrap around the drive pin 2044. The bent configuration 2320 consisting of two bends in the spring 2015 can engage the capture feature 2040, such as Fig.23 As shown. The distal end of the spring 2015 can be connected to the reel 2020 or the protrusion 2060 by an adhesive 2310. The reel 2020 can in turn be attached to the strip 1815 by an adhesive 2305. No limitation to a particular type of fixation or adhesive should be inferred. This transmits the spring 2015 force from the capture feature 2040 in the winder box frame 2030 through the curved configuration 2320 of the spring 2015. The winder box frame 2030 is attached to the spring 2015, which is interlocked to the reel 2020 via the protrusion 2060, and the reel in turn adheres 2305 to the strip 1815, thereby tensioning the assembly. The action of rotating the angle magnet 2025 relative to the angle magnetic sensor 1940 as the limb expands and contracts can be achieved using this tensioning mechanism.

[0169] Fig.24 24 is a side view of a device, which may correspond to device 1900. In practice, device 1900 may drift to its operable, repeatable initial position on the limb due to the effects of gravity and patient movement, such as due to friction between strap 1815 and the limb.

[0170] Fig.25 It is taken along line BB Fig.24A detailed cross-sectional view 2500 of the measurement assembly 1805, winder box 1810, strap 1815, and fastener 1820 of the example device shown. This demonstrates the engaged use position of fastener 1820 with cover 1905 and the position of battery 1910 in housing 1935. A 3:1 scale is indicated to give a sense of the size of the device that may correspond to device 1900. However, the scale will vary depending on the size of the figure presented on the page. That is, zooming in or out will affect the scale, and therefore 3:1 should not be considered limiting.

[0171] exist Fig.25 The right side of the embodiment of the present invention has the winder box 1810 in its use position. The winder box frame 2030, the reel 2020, the spring 2015, the angle magnet 2025 and the drive pin 2044 work together to communicate the rotation of the reel 2020 and the total length measured around the circumference of the wearer's limb, as determined as described elsewhere herein.

[0172] Fig.26 is an isometric view of an apparatus 2600, which may correspond to Fig.18 The device 1800 shown has the housing of the measurement assembly removed. The view orientation shows the electronics in close proximity to the limb with the rear housing 1935 removed (for illustration purposes only). There may be components on the electronics subassembly 1915 for sensing physiological parameters such as heart rate, SPO2, NIBP, etc. In the example shown, a light emitter 2615 that can emit green, red, and infrared wavelengths of light is placed in the center and in close proximity to the wearer. The light from the emitter component enters the wearer's skin. Some of this light is reflected back and sensed by the detector components 2605 and 2610. The returned light is sensed and evaluated by software. The original measurement or the evaluated measurement can then be transmitted to other computing devices.

[0173] In some embodiments, the device 1900 can use the orientation information detected by the accelerometer to detect when the patient is in a supine position or resting. The resting heart rate is sampled. It is known that changes in resting heart rate vary with patient fluid retention. These heart rate readings can be used to increase confidence in the interpretation of the circumference measurement.

[0174] Limb circumference measurements and limb orientation data may be continuously acquired at regular intervals and processed to produce a personal daily swelling pattern for the subject wearing the device. The daily swelling pattern is characterized by a minimum limb circumference occurring when the subject is lying down, and a maximum limb circumference after the subject has been in an upright position (such as standing or sitting) for a period of time specific to the individual.

[0175] The trend of fluid gain or loss can be calculated over a specified time period (e.g., days, weeks, or months). Fluid gain / loss and fluid gain / loss trends can be compared to thresholds to identify conditions of concern. The system takes specific actions for conditions of concern, including sending messages and alerts to the user and support personnel (e.g., family caregivers, chronic care managers, and / or clinical staff).

[0176] The rate at which body fluid redistributes itself in the body as it rises to a vertical orientation can indicate the viscosity of the interstitial fluid; changes in viscosity are known to be associated with decompensation of heart failure due to changes in protein levels in the interstitial fluid. This is typically assessed by a physician pressing a finger firmly against the patient's ankle and observing whether the resulting "indentation" rebounds quickly. If the indentation rebounds slowly, the condition is described as pitting edema. This is an important medical sign and a useful diagnostic method to characterize the patient's condition.

[0177] The disclosed technology can characterize the rate of change of redistribution of interstitial fluid. By taking multiple measurements as the patient moves from a supine orientation to an upright orientation (typically in the morning), the time required for interstitial fluid redistribution associated with changes in the direction of gravity can be tracked. This rate of change measurement is directly related to the viscosity of the interstitial fluid. Being able to identify interstitial fluid viscosity and changes associated therewith can further inform medical practitioners or computational algorithms of changes in a patient's disease state, as body fluid viscosity provides insight into the root causes of body fluid load (e.g., changes in protein levels in the interstitial fluid).

[0178] Although the subject matter has been described in specific language of structural features and / or methodological acts, it should be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or acts described above. Instead, the specific features and acts described above are disclosed as example forms of the claims that are about to be proposed.

Claims

1. A device for determining the level of interstitial swelling in a subject, the device comprising: A winder box, the winder box comprising: frame; a capture feature supported by the frame, the capture feature including a drive pin, and the drive pin having a first spring coupler; a spring coupled to the capture feature via the first spring coupler; and a spool supported by the frame and surrounding the spring, the spool supporting the first magnet and having a second spring coupler via which the spool is coupled to the spring; and A measurement assembly, the measurement assembly comprising an electronic device subassembly, wherein the electronic device subassembly comprises: measurement components, the measurement components comprising a first magnetic sensor arranged to be magnetically coupled to the first magnet; one or more processors; a memory; and executable instructions stored in the memory, which, if executed by the one or more processors, cause the one or more processors to perform operations, the operations comprising: determining a first measurement of a first magnetic coupling between the first magnet and the first magnetic sensor; determining a first angle of a spool around which the strip is wound based on the first measurement; determining the number of revolutions of the reel; determining a length of the strip to be unwound from the spool based on the first angle and the number of revolutions of the spool; A first circumference representing the volume of interstitial fluid is determined based on the length of the strip unrolled from the spool.

2. The apparatus of claim 1, further comprising: at least one interrupt circuit comprising a magnetic sensor and generating an interrupt to one of the one or more processors, In response to the interrupt rate exceeding a preset threshold, the one of the one or more processors enters a predefined state.

3. The device according to claim 3, wherein: The predefined state is the awake mode.

4. The device as claimed in claim 3, wherein: The predefined state is broadcast mode.

5. The apparatus of claim 1, further comprising: a magnetic sensor configured to output at least two analog signals associated with the angular position of the reel, and at least one interrupt circuit, the at least one interrupt circuit comprising a magnetic sensor, Wherein, in response to detecting an interruption associated with a full rotation of the reel, the number of revolutions is confirmed using an angle of the reel determined based on the angular position.

6. The apparatus of claim 1, further comprising: a second magnet, the second magnet being supported by the frame, wherein the measuring components further include a second magnetic sensor arranged to be magnetically coupled to the second magnet, and wherein the operations further include: determining a polarity of a second magnetic coupling between the second magnet and the second magnetic sensor; and Based on the polarity the maximum stretch of the strip is determined.

7. The device of claim 1, wherein: The first spring coupler includes a protrusion configured to couple to a corresponding first aperture in the spring, and the second spring coupler is a protrusion configured to couple to a corresponding second aperture in the spring.

8. A computer-implemented method for determining an increase or decrease in interstitial volume in a subject, the method comprising: via one or more magnetic sensors in a winder cassette, the winder cassette comprising a frame; a capture feature supported by the frame, the capture feature comprising a magnet; a spring supported by the capture feature; and a spool supported by the frame and surrounding the spring, the spool supporting the magnet; and a measurement assembly comprising an electronics subassembly, wherein the electronics subassembly includes measurement components including a magnetic sensor arranged to be magnetically coupled to the magnet; one or more processors; a memory; and executable instructions stored in the memory that, if executed by the one or more processors, cause the one or more processors to perform operations including: determining a measure of magnetic coupling between the magnet and the magnetic sensor; determining a first diameter of a spool around which the strip is wound based on the measured value, the first diameter comprising a diameter of the spool itself plus a winding thickness of the strip wound on the spool; determining a first circumference of the wound spool based on the first diameter; determining a length of the wound strip on the spool based on the first circumference, the length being the full length of the strip minus the amount by which the strip is wound on the spool; and The level of interstitial swelling was determined based on this length.

9. The method of claim 8, further comprising: determining that a change in the circumference of the strip on the wound reel exceeds a preset length threshold; as well as In response to determining that the circumference change exceeds the preset length threshold, at least one processor among the one or more processors is triggered to enter a predefined state.

10. The method of claim 9, wherein: The predefined state is the awake mode.

11. The method of claim 8, further comprising: determining an interrupt rate of a processor of the one or more processors; as well as In response to the interrupt rate exceeding a preset threshold, triggering the one of the one or more processors to enter a predefined state.

12. The method of claim 11, wherein: The predefined state is the awake mode.

13. The method of claim 8, further comprising: determining that a change in the circumference of the strip on the wound reel exceeds a preset acceleration threshold; as well as In response to determining that the circumference change exceeds the preset acceleration threshold, a processor among the one or more processors is triggered to enter a predefined state.

14. The method of claim 13, wherein: The predefined state is the awake mode.

15. The method of claim 8, further comprising: The determination of the level of interstitial swelling is integrated with automated real-time control of therapy for that patient.

16. One or more non-transitory computer-readable storage media comprising executable instructions that, if executed by one or more processors, cause the one or more processors to perform operations to determine an increase or decrease in interstitial volume of a subject via one or more magnetic sensors in a winder cassette, the winder cassette comprising a frame; a capture feature supported by the frame, the capture feature comprising a magnet; a spring supported by the capture feature; and a spool supported by the frame and surrounding the spring, the spool supporting the magnet; and a measurement assembly comprising an electronics subassembly, wherein the electronics subassembly comprises measurement components comprising a magnetic sensor arranged to be magnetically coupled to the magnet; the one or more processors; and a memory, the operations comprising: determining a first measurement of a first magnetic coupling between the first magnet and the first magnetic sensor; determining a first angle of a spool around which the strip is wound based on the first measurement; determining the number of revolutions of the reel; determining a length of the strip to be unwound from the spool based on the first angle and the number of revolutions of the spool; and A first circumference representing the volume of interstitial fluid of the subject is determined based on the length of the strip unrolled from the spool.

17. The one or more non-transitory computer-readable media of claim 16, the electronics subassembly further comprising at least one interrupt circuit, the at least one interrupt circuit comprising a magnetic sensor and generating an interrupt to one of the one or more processors, the operations further comprising: Determine the interrupt rate; as well as In response to the interrupt rate exceeding a preset threshold, triggering the one of the one or more processors to enter a predefined state.

18. One or more non-transitory computer-readable media as recited in claim 17, wherein: The predefined state is the awake mode.

19. The one or more non-transitory computer-readable media of claim 17, wherein: The predefined state is broadcast mode.

20. The one or more non-transitory computer readable media of claim 16, the operations further comprising: The determination of the level of interstitial swelling is integrated with automated real-time control of therapy for that patient.

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